Prevalence of spotted fever group rickettsiae in ticks from southern Israel.

The prevalence of spotted fever group rickettsiae was studied in questing ticks collected from southern Israel. Ticks were examined from an agricultural settlement (kibbutz Ze'elim), an endemic site for Mediterranean spotted fever, and from another kibbutz (Re'im) in an adjacent area where the disease has not been reported. Ticks were collected by flagging and CO2 traps from vegetation inside and outside the settlements during 1989/1990 and 1994. In Ze'elim, 98% of the ticks collected were brown dog tick, Rhipicephalus sanguineus (Latreille), whereas in Re'im the predominant species was Rhipicephalus turanicus Pomerantzev (84.6%), with 11.8% of the ticks R. sanguineus and 3.6% Hyalomma excavatum Koch. The presence of rickettsiae in the hemolymph of the ticks was demonstrated by immunofluorescence using polyclonal antibodies made against the human pathogenic Moroccan strain of Rickettsia conorii. Of 549 ticks examined in 1989/1990 from Ze'elim, 7.3% were positive for spotted group rickettsiae, and in Re'im 2.2% of 156 R. turanicus were positive. In 1994, 51 out of 186 (27.4%) ticks in Ze'elim and 3 out of 115 (2.6%) ticks in Re'im were positive. All 20 specimens of H. excavatum were negative for spotted fever group rickettsiae. To our knowledge, this is the 1st report of spotted fever group rickettsiae in R. turanicus from Israel.